Number of patients with adequate ventricular rate control following the start of medication during the 24-week Follow-up Period

Total number of hospitalization days per patient (all-cause) following the start of study medication during the Total Study Period (24 weeks). Hospitalization was defined by a hospital admission (note that same day admit and discharge equates to 0 days duration), ER visits were not counted as events.

metoprolol succinate (Toprol-XL)

Participants were randomized (1:1) to blinded treatment with bucindolol or metoprolol and titrated weekly to target doses of 50 mg twice daily (BID; < 75 kg) or 100 mg BID (≥ 75 kg) for bucindolol or 200 mg once daily (QD) for metoprolol. The starting dose of bucindolol was 6.25 mg BID with weekly dose titrations to the target dose or to the maximum tolerated dose. The bucindolol target dose varied based on the patient's weight on the day of randomization: patients < 75 kg receiving a target dose of 50 mg BID (100 mg daily) and patients > 75 kg receiving a target dose of 100 mg BID (200 mg daily).

Capsules were available for titration in the following dosage strengths to be taken twice daily (with or without food): 25mg, 50mg, 100mg, 200mg and/or matching placebo oral capsule to maintain blinded dosing.

Blinding will be accomplished by providing study drug (i.e., bucindolol or metoprolol tablets) in capsules that are visually indistinguishable and provided in numbered kits. Only the numbers of the kits to be administered to a given patient, and not the identity of the study drug, will be provided to sites. Investigators, site personnel, and patients will not be informed of the blinded study drug assignment at the time of study completion.

Either Bucindolol 6.25mg BID or Metoprolol XL 25mg QD

Either Bucindolol 12.5 mg BID or Metoprolol XL 50 mg QD

Either Bucindolol 25 mg BID or Metoprolol XL 100 mg QD

Either Bucindolol 50 mg BID or Metoprolol XL 200 mg QD

Bucindolol taken twice daily. Starting dose of 6.25 mg, 12.5 mg, 25 mg, or 50 mg bid depending upon pre-study beta-blocker dose. Sites instructed to uptitrate to target dose of 50 mg bid (subjects < 75 kg) or 100 mg bid (subjects >= 75 kg). Metoprolol succinate taken once per day and a placebo capsule taken once per day. Metoprolol succinate starting dose is 25 mg daily with dose titrations until 200 mg once daily or the maximum tolerated dose is achieved.

Sponsor requested that the last visit be between Aug-Dec 2017 and therefore a number of participants completed this arm prior to 24 week and are noted as sponsor or investigator initiated.

Sponsor requested that the last visit be between Aug-Dec 2017 and therefore a majority of participants were not enrolled in this treatment extension period.